Soil stabilizing agent comprising an acid sludge-sulfuric acid product and method for preparing the agent

ABSTRACT

Disclosed is a soil stabilizing agent consisting of a source of calcium, such as calcium carbonate, and a spent sulfuric acid, in a water solution and a method for applying the same. Certain chloride and sulfate materials, such as aluminum and ferric chloride and aluminum and ferrous sulfate, may be added to the soil with the stabilizing agent to provide enhanced results in particular soils. The stabilizing agent is applied with sufficient water to thoroughly wet the soil and thus disperse the agent through the soil and the treated soil is then worked to accomplish thorough mixing. An alternate method of application is also disclosed in which the calcium source material, and the chloride or sulfate materials if used, are applied dry in powdered or granular form to the soil surface, the soil and materials are treated with a solution of water and a spent sulfuric acid sufficient to thoroughly wet the soil to the desired depth of treatment and disperse the chemicals therein, and the chemicals and soil are then worked until thorough mixing is assured.

HU 1.1.) CA

United States Patent 91 Schneider Apr. 8, 1975 1 1 SOIL STABILIZINGAGENT COMPRISING [76] Inventor: Gordon L. Schneider, 5546 E.

Donner, Fresno. Calif. 93727 [22] Filed: Dec. 29, 1972 [21] Appl. No.:319,455

[52] U.S. Cl. 106/287 SS; 106/274; 106/90 [51] Int. Cl. COSh 17/46; C04b11/14 [58] Field of Search 106/287 SS, 123, 90. 109;

156] References Cited UNITED STATES PATENTS 8/1934 Hall 196/41 5/1942Chechot 196/40 2.315.044 3/1943 Bronsky 208/266 3.470.006 9/1969 Brunel106/123 FOREIGN PATENTS OR APPLICATIONS 618.114 4/1961 Canada 106/287 SSPrimary Examinen-Theodore Morris Attorney, Agent. or Firm-Mason,Kolehmainen, Rathburn 8L Wyss 5 7 ABSTRACT Disclosed is a soilstabilizing agent consisting of a source of calcium, such as calgi umcarbonate, and a spent sulfuric acid. in a wate solution and a methodfor applying the same. Certain chloride and sulfate materials, such asaluminum and ferric chloride and aluminum and ferrous sulfate, may beadded to the soil with the stabilizing agent to provide enhanced resultsin particular soils. The stabilizing agent is applied with sufficientwater to thoroughly wet the soil and thus disperse the agent through thesoil and the treated soil is then worked to accomplish thorough mixing.An alternate method of application is also disclosed in which thecalcium source material, and the chloride or sulfate materials if used.are applied dry in powdered or granular form to the soil surface. thesoil and materials are treated with a solution of water and a spentsulfuric acid sufficient to thoroughly wet the soil to the desired depthof treatment and disperse the chemicals therein. and the chemicals andsoil are then worked until thorough mixing is assured.

17 Claims, No Drawings SOIL STABILIZING AGENT COMPRISING AN ACIDSLUDGE'SULFURIC ACID PRODUCT AND METHOD FOR PREPARING THE AGENT RELATEDAPPLICATION This application is a continuation-in-part of my copendingapplication Ser. No. 89,006 filed Nov. 12, 1970 (now abandoned),entitled A Soil Stabilizing Agent and Method of Stabilizing Soils. whichis continuation-inpart of my copending application Ser. No. 745,957filed July 19, 1968 (now abandoned), which is a continuation-in-part ofmy copending application Ser. No. 508.925 filed Nov. 22, 1965 (nowabandoned), which is a continuation-in-part of my copending applicationSer. No. 360.114 filed Apr. l5. 1964 (now abandoned).

BACKGROUND OF THE INVENTION The present invention relates generally tocompounds and methods for stabilizing soils, and more particularly tostabilizing agents and methods for application thereof which areeffective in stabilizing finely divided soils such as clays and silts(hereinafter collectively referred to as finely divided soils).

The construction of roadways, streets, parking lots, aircraft runwaysand the like of finely divided soils is difficult and expensive becauseof the inherent instability of such soils. The stabilization of soilswith high organic content such as Chernozems, Andos. brunizems. Podzols.alluvial and bog soils (hereinafter collectively referred to as organicsoils") also presents a substantial problem. Some soils. of course. area combination of both.

For many years a common approach to stabilizing such soil has been toincorporate borrow materials into the soil. Gravel and other granularmaterials, for example. have been commonly used in silts and clays withbeneficial results. Crushed rock because its angular characteristicsprovided both good support and good drainage, has been widely used asborrow material in all types of soils where it was economicallyavailable.

In addition to borrow materials, stability has been enhanced in finelydivided soils by the use of lime, cement and asphalt. In some cases,these coumpounds have been used to supplement the borrow materialsbecause of their ability to modify the unstable characteristics of thesoil. Cement has proven best in the silts and the very fine sands, whileasphalt has been most effective in the coarser sands and for use withrock and gravel borrow materials. Lime has proven to be effective instabilizing the true clays but unsatisfactory in silts and organicsoils.

Lime-fly ash compositions have been utilized to improve the stability ofborrow materials containing appreciable quantities of finely dividedsoils but have proven disappointing as a means of stabilizing true claysand silts. where no appreciable aggregate is present. and soilscontaining significant proportions of entrained organic residues.

Although all of these materials have helped resolve the difficult andexpensive job of stabilizing finely divided soils and organic soils, inone way or another. each has its limitations and a considerablechallenge still remains.

Borrow materials, for instance, are frequently not available withouttransport over great distances, which renders their use quite costly ifnot totally impractical. Cement and lime. used either alone as anadditive to the native soil, or as a supplement to a grandular borrowmaterials, are expensive and difficult to apply in the quantitiesrequired. Asphalt is restricted in the more granular types of soil whereit is helpful to stability and the lime-fly ash product is not helpfulexcept where certain borrow materials are available.

It has long been evident that the chemistry of a soil has an importantrelationship to its stability characteristics and that chemicallyaltering a soil can improve its stability. Prior to this disclosure,however, the economical and versatile manner provided has not beenavailable.

The broad essence of the present invention resides in the discovery thatapplying to a finely divided soil, materials known to have a beneficialeffect on the stability of such soils, and particularly a source ofcalcium (although magnesium or potassium can be quite effective incertain soils) with a reduction-oxidation stimulating compound such as aspent sulfuric acid, and substantial quantities of water (hereinafterreferred to as reaction product), initiates rapid and substantialchanges in the soil characteristics which greatly enhance its stability.Moreover, such changes can be accomplished even where the quantities ofthe chemicals applied and the methods of applying them are considerablyless costly than the presently known stabilization approaches describedabove. and provide additional beneficial results including a significantreduction of the plasticity index and a substantial increase in the wetstrength. By the addition of certain ancillary products to the reactionproduct of the invention, particularly certain chloride and sulfatecompounds, it is also possible to substantially reduce. or eveneliminate. shrinkage and swell of such soils and to reduce theplasticity index even further.

The soil stabilizing agent of the present invention combines certain ofthe properties of lime. or CaO, with some of those characteristic ofasphalt. and at the same time functions as a reducing-oxidizing agent onorganic matter in the soil. Because of chemical reactions initiated bythe reducing-oxidizing agent, small quantities of calcium and othermaterials known to be beneficial to soil stabilization can be made to doa job which would require considerably greater quantities under the oldapproaches. The reaction product is quite compatible with asphalticmaterials and can make those materials more effective as well. In sandysoils. the reaction product and asphalt make a particularly effectivecombination. Of course, my soil stabilizing agent can be effectivelyemployed without asphaltic materials, and in some soil situations shouldbe.

In solving soil stability problems, my reaction product is the keymaterial, and, while by itself it does not materially reduce theshrinkage and swelling of expansive clays, when used in conjunction withcertain ancillary products of the present invention it can accomplishthis. These otherproducts are essentially mixtures of sulfates in onecase and mixtures of chlorides in another. For convenience, theancillary products will be hereinafter referred to as the sulfateproduct" and the chloride product".

The reaction product is also highly compatible with naturally occurringcarbonates. When properly applied, very high stability at low cost isachieved. At times, the use of the reaction product can do a job whichis virtually impossible otherwise to accomplish. The use of theancillary products of the present invention in conjunction with thereaction product can eliminate or rectify soft spots and frost damagedareas.

The following US. Pat. Nos. were cited against the patent applicationsof which this is a continuation-inpart:

2.705.681 Wishlinski Bituminous Composition and Process of Making It2.833.663 Jenkins et al Method of Making Asphalt Emulsions 2,675.329Schuessler Preparation of Metal Sulfonate Composition 243.167 Samman ctal Soil Stabilization (Australian) These patents serve to characterizethe prior art with which the present invention is clearly contrasted.Each requires a high pH and relies on saponification to achieve itspurpose. The present invention requires a low pH. preferably below 2.0does not involve saponification and achieves markedly superior resultsfor its intended purposes, as will subsequently become apparem.

SUMMARY OF THE INVENTION It is therefore an object of the presentinvention to increase the wet strength of finely divided soils, andsoils containing substantial quantities of organic residues.

Another object is to reduce the plasticity index of such soils.

Another object is to restrict the speed with which water enters thestructure of such soils during periods of wet weather or thawing, and toreduce the speed which moisture leaves during periods of dehydration.

Another object is to provide a product and methods for its applicationwhich can be used to prevent soil erosion until a vegetative cover cantake over.

Another object is to provide a product and methods for its applicationwhich are beneficial when applied to load bearing subbases and subgradesin finely divided soils. even when substantial quantities of organicresidue are present.

Another object is to provide a product and methods for its applicationto bases with excessive fines to improve the wet strength thereof.

Another object is to provide a product and methods for its applicationwhich can achieve stabilization of the soil of shoulders. slopes andbackfills.

Another object is to provide a product and methods for its applicationwhich is highly effective in the repair of soft spots and frost damagedareas in paving and other load bearing surfaces.

Another object is to provide a product and methods for its applicationwhich can increase the permeability of average clay soils and reduce theshrinking and swelling thereof incident to water release and absorption.

Another object is to provide a product and methods for its applicationwhich can greatly increase the permeation rate of water throughexpansive type clays and materially reduce the swell and shrinkage ofsuch clays.

Another object is to provide a product and methods for its applicationwhich can achieve selective control over the undesirable properties ofclay soils, including soils containing substantial quantities of organicresidues.

These and other objects and advantages will be more readily apparentfrom the following description of a preferred embodiment of the reactionproduct which is achieved by interacting a source of calcium and aproperly selected or conditioned spent sulfuric acid. The chemicalreaction of the constituents is brought about either by adding them to aquantity of water in a mixing tank under conditions which control theaddition of the ingredients and the exothermic reaction resultingtherefrom, and then applying the product to the soil in predeterminedwater diluted proportions, or by blending the chosen calcium sourcematerial into the soil surface and then applying the water and spentsulfuric acid. In either case, the reaction product is applied to thesoil with sufficient water to thoroughly wet the soil being treated anddisperse the reaction product, and is thoroughly mixed with the soil.

DESCRlPTlON OF THE EMBODIMENTS Reaction Product The naturally occuringcarbonates are the principal sources of soil stabilizing materials forfinely divided soils, primarily calcium carbonate, CaCo Most of thesecarbonates are utilized as quick lime, CaO, or hydrated lime, Ca(OH)Calcium carbonate is almost completely isoluble in water and will gointo solution only when hydrogen ions or a surplus of carbon dioxidemolecules are present. Hydrated lime, on the other hand, is completelywater soluble.

It is impossible to grind or crush carbonates or lime to a point wherethey are fine enough to be individual molecular particles. It is alsoimpossible to agitate or stir the particles into the soil mechanicallyto a point where they can be physically separated molecule by molecule.Nevertheless, it is possible to do this, to a large extent. during theprocess of formulating the carbonates or lime into a product. This isdone in the production of the reaction product of the present inventionand results in a soil stabilizing agent greatly superior to calciumcarbonate or lime in its ability to stabilize finely divided soils evenwhere organic residues are present in substantial quantities.

The chemical structure of the reaction product is believed to be that ofdiscrete particles or molecules consisting of an atom of calcium, anorganic radical with a carbon chain of twelve or more depending upon thetype of hydrocarbon present, and a sulfate or sulfonate component beingprincipally sulfonates, all surrounded by a cationic solution of waterand organic sulfonates or sulfates that are the surplus or excess addedto bring the pH to a low level. The cationic solution surrounding thesemolecules can contain emulsified particles of oil or asphalt wheresupplemental quantities of oil or asphalt are added or present in thespent sulfuric acid.

The molecular structure of the product appears to be:

(H o m Where R an aliphatic or aromatic hydrocarbon or a combination ofboth, and X a number having a value from about 0.5 to about 1.0, and Y anumber having a value from about 0.5 to about 2.0.

Preliminary to providing specific examples of the present invention,attention is invited to the meaning of certain terms utilized herein. Asthey are well known in the art, the following terms are intended to havethe following meanings:

"Petroleum oil liquid mineral hydrocarbons consisting of mixtures ofparaffin, naphthene, and/or aromatic hydrocarbons.

"Asphalt" bituminous and petroleum tars, oils and pitches utilized inbinding aggregate particles in the formation of stabilized soil and roadpaving.

Kerosene" a distillate of petroleum oil having approximately thefollowing characteristics: APl gravity, 50 to 35 deg., at 60F; sp gr,0.78 to 0.85 at 60/60F; closed-cup flash point, 100 to 160F; hhv, 19,400to 20,200 Btu per lb", distillation range, 200 to 600F', chemicalcomposition, 85 to 88 percent carbon, 15 to 12 percent hydrogen, up to0.5 percent sulphur, and, usually negligible percentages of nitrogen andoxygen.

Diesel Oil" a distillate of petroleum oil having approximately thefollowing characteristics: APl gravity from 40 to 17.5 deg at 60F; sp grfrom 0.82 to 0.95 at 60/60F; hhv from 18,500 to 20,000 Btu per lb;distillation range from 350 to 700F or higher; ultimate composition,carbon 85 to 88 percent, hydrogen 15 to percent, sulphur up to 2percent, combined oxygen and nitrogen up to 2 percent.

Stove or Fuel Oil a distillate of petroleum oil having approximately thefollowing characteristics: APl gravity from 40 to 10 deg at 60F; sp. gr.from 0.82 to 1.00 at 60/60F; hhv from 18,000 to 20,000 Btu per lb;distillation range from 350 to 700F and higher; chemical composition,carbon 85 to 90 percent, hydrogen to 8 percent, sulphur up to 2 percent,combined oxygen and nitrogen up to 2 percent.

Sulfuric acid sludge" waste or spent sulfuric acid usually resulting asa by-product from refining petroleum oils or benzene. The acid treatmentof oils which form sulfuric acid sludges is usually performed to improvethe color or quality of the oil During such treatment the acid graduallybecomes ineffective as it becomes loaded with various hydrocarbon chainfragments that are seized because they are lacking a hydrogen atom thatotherwise would protect the carbon beneath from acid attack. Theirformation is described in US. Pat. No. 2,705,681. However, in the patentthey are neutralized subsequent to formation in direct contrast to theirutilization in the present invention. Although sulfuric acid sludge" ischemically complex and virtually impossible to define chemically, it iswell known in the art. For example, authors Kalichevsky and Kobe inPetroleum Refining with Chemicalsstate:

The composition of sulfuric acid sludges is very complex. Sludgescontain many reaction products not found in crude oils and undergoconsiderable changes in chemical composition on standing. This isdemonstrated by changes in the physical appearance of the sludge and bythe evolution of sulfur dioxide.

The sulfuric acid sludges contain sulfuric acid esters, sulfonic acids,salts of nitrogen bases, resinous and asphaltic materials, sulfurcompounds dissolved from the oil, hydrocarbon polymers, condensationproducts and entrained oil. The composition varies with the nature ofthe crude oil fraction, treating conditions and time of storage. Sludgeis an emulsion formed by two dispersed phases included in an organicdispersion medium."

Spent Acid Sludge and Spent Sulfuric Acid" a sulfuric acid sludge"resulting from petroleum refinery processes, such as alkylation andisomerization. Such processes utilize highly concentrated sulfric acid.The alkylation process uses a sulfuric acid of 98 percent concentration,the acid serving as a catalyst in the process. Although the concentratedacid functions as a catalyst during the alkylation process, the acidultimately becomes diluted by entrained or absorbed hydrocarbons so thatthe concentration falls below a minimum effective level of 88 to 92percent. In such a diluted state it is a brown or mahogany colored fluidliquid that will, upon standing for a period of time. gradually turnpurplish or black in color. It is generally designated in the petroleumindustry as spent acid sludge or a mahogany sulfonate. Such a spent acidsludge typically has an acidity of approximately to 92 percent andcontains about 4 to 10 percent hydrocarbons and about 0.1 0.3 ash.

Ash" the mineral content which remains after a product has been burned.

A preferred embodiment of the reaction product of the present inventionis formed by adding calcium carbonate to an adequate supply of water andthen mixing in spent sulfuric acid. The spent sulfuric acid should beaged to the stage of its purplish color and must be added at acontrolled rate to limit the resulting heat since the reaction isexothermic. Kerosene or diesel oil may be added to limit the vigor ofthe exothermic reaction and enhance the performance of the product.

The following specific examples are illustrative of the production of myreaction stabilizing agent.

EXAMPLE I 1,458 parts of water by weight of water. 175 parts by weightof diesel oil. 950 parts by weight of calcium carbonate. 3,058 parts byweight of spent acid sludge of about 78 percent acidity.

EXAMPLE 11 The same as EXAMPLE 1 except about 210 parts of diesel oil,about 900 parts of calcium carbonate and about 2,752 parts of acidsludge are utilized.

EXAMPLE Ill The same as Example 1 except About 1,666 parts of waterAbout parts of diesel oil About 800 parts of calcium carbonate About3,058 parts of acid sludge.

EXAMPLE IV 12 parts by weight of water 2 parts by weight of kerosene 7parts by weight of calcium carbonate 12 parts by weight of spent acidsludge which is approximately 80 percent acid and 10 percenthydrocarbons pl-l attained 1.55 8.6. 1.52

EXAMPLE V l2 parts by weight of water 7 parts by weight of calciumcarbonate l parts by weight of spent acid sludge which is approximately55 percent acid and 30 percent hydrocarbons 8 parts by weight 66 Baumesulfuric acid pH attained L68 5.6. 1.44

EXAMPLE Vl l4 parts by weight of water 8 parts by weight of calciumsulfate l0 parts by weight of spent acid sludge (30 percent acid and 50percent hydrocarbons) 8 parts by weight of 66 Baume sulfuric acid pHattained 1.56 8.6. 1.48 In Examples V and VI note no addition of oil andthe use of sulfuric acid and calcium sulfate to control the pH, thelatter material also serving as the calcium SOUTCC.

EXAMPLE VII 12 parts by weight of water 2 parts by weight of kerosene 7parts by weight of calcium carbonate parts by weight of spent acidsludge (80 percent acid and 10 percent hydrocarbons) Since sulfuric acidsludges can vary considerably in the amount of sulfuric acid content,only a sludge having a sulfuric acid content of at least 75 percent canbe used when it is the sole source for the acid. However, in order toutilize various spent acids in the interest of economy, especially thesludges resulting from lubricating oil operations, it is possible toadjust the pH of the sludge by substituting sulfuric acid of 60 Baume orhigher concentration for sludge to the extent necessary to bring the pHinto the desired range, or by substituting sludge containing a higherpercentage of sulfuric acid for a portion of the sludge being used inorder to accomplish the same result, or by substituting calcium sulfatefor calcium carbonate to the extent necessary to reduce the pH to therange desired, or by adding sulfuric acid in conjunction with calciumsulfate to bring the TABLE 1 Type of Z 1 Hydro- Add Add Add Acid SludgeAcid carbons Oil Acid CaSO,

Alkylation 85 5 X Dichlorodyphenyltrichloroethane 75 X X Sulfonation 50X Lubricating Oil X X LII The lubncating O1] and sludges at roomtemperature are highly viscous, whereas spent acid sludges are quitefluid. Therefore, when the former are used in the manufacture of thereaction product, it is sometimes necessary to preheat the water and tomix vigorously to obtain a better blending action while introducing theoil and calcium carbonate. When the exothermic reaction begins to raisethe temperature, the cooling water should be circulated to hold down thetemperature of the mixture.

Various sources of calcium can be employed in producing the reactionproduct of the present invention. Calcium carbonate CaCO quicklime CaO,calcium hydroxide or slaked lime Ca(OH) are true chemical equivalentsexcept for the absence of one CO molecule in the lime and the additionof one molecule of water in the case of slaked lime. Portland cement,which has proven to be as effective as lime, is another source ofcalcium but is not a true chemical equivalent. The approximate chemicalformula for Portland cement is 3CaO.Al O Calcium fluorapatite, which hasthe approximate chemical formula of CaF- Ca (PO,) and calcium phosphateCa (PO,) appeared to be equally effective as sources of calcium. Calciumsulfate (gypsum) CaSO H O, is another source of calcium which is veryeffective and of great value in those sludges where thesulfuric acidcontent is low. Calcium chloride was not found to be beneficial.probably because of competition between the sulfur and the chlorineduring processing of the product.

In certain types of soils the addition of petroleum oil or asphalt wherethe acid sludge does not contain an appreciable amount of entrainedhydrocarbons results in a superior reaction product. The best results incertain coarser soils, for instance, was obtained with those reactionproducts in the above Examples which included the addition of keroseneor diesel oil.

The heavier oils and asphalts have been determined to act as cementingagents in themselves, especially when used in conjunction with the soilstabilizing chemical reaction product of the present invention which hasproven to possess the unique ability of dispersing asphalts and tars toa point where they can now be used in clays as stabilizing materials,whereas in the past they have always failed to accomplish such apurpose. This is because the reaction product of the present inventionacts as a cationic emulsifying agent for such heavier oils and asphalts.Thus, asphalts are readily emulsified even at average watertemperatures. By using asphalt to supplement the action of the reactionproduct, a low cost stabilization is achieved, especially effective insilts. This high compatibility with asphalts, road oils, and tar insilts and clays is one of the several significant features of thereaction product of the present invention.

From the standpoint of the quality of the finished reaction product, theorder of preferred oils utilized in the formation of the reactionproduct is (l) kerosene; (2) light diesel oil; (3) diesel oil; (4) lightdistillate oil; (5 distillate oil; (6) gas oil; (7) aviation jet fuel;(8) residual fuel oil or asphalt. That is, beginning with the preferredkerosene, the desirability of these oils decreases as the distillationtemperature and the specific gravity of these petroleum productsincreases. Products from the lighter petroleum fractions, such asgasoline, naphthas, benzene, toluene, zylene, and mineral spirits, arealso effective informing the reaction product of the present inventionbut their high cost and generally hazardous nature probably precludetheir commercial use.

Oil is essential for a good quality reaction product when spent acidsludges are used with low hydrocarbon content. However, the amount to beadded depends upon the amount of hydrocarbons entrained in the acidsludge, which should be at least three percent. The ad dition of oil isnot essential where the amount of hydrocarbons in the acid sludge isequal to or in excess of 20 percent by volume of the total amount ofacid sludge used. Preferably, the hydrocarbon content of the tinishedproduct should not exceed 30 percent. The following table lists acidsludges with different hydrocarbon content and indicates the minimumamount of oil needed to be added, the percentages being based on avolume relationship and not by weight.

For quantity production of about 400 gallons of reaction product inaccordance with Example I, the constituents are intermixed as follows.

175 Gallons (about 1,458 pounds) of water and about 25 gallons (I75pounds) of diesel oil are introduced into a mixing tank. Approximately950 pounds of calcium carbonate are mixed with the water and oil.Thereafter, while the mixing continues, approximately 200 gallons (3,058pounds) of spent acid sludge of about 78 percent acidity and 10 percentintrained hydrocarbons is added at a gradual rate to prevent excessivetemperatures or boiling over" due to too rapid emission of gases whichconsist principally of carbon dioxide. The temperature of the mixture inthe tank is maintained at a point below l80F., and preferably in therange of 140 to l50F. The mixing of the ingredients results in a highlyexothermic reaction during which considerable heat is generated, andwater vapor with a mixture of gases, including sulfur dioxide,mercaptans and carbon dioxide, are lost to the atmosphere.

As the pH drops with the addition of the acid sludge, the mixtureprogressively thickens until a pH of 7 is reached. Thereafter, themixture again becomes more fluid as more acid sludge is introduced andthe pH drops lower and lower. Therefore, the amount of water used isthat amount necessary to keep the mixture from becoming too viscous at apH of 7. The amount of yield is about 90 percent of the total weight ofingredients with the dry solids representing from 17.5 to percentthereof. The mixing tank is preferably equipped with a coil or jacket,through which cooling water is circulated, and with mixers to assurethorough blending.

METHOD OF APPLYING REACTlON PRODUCT Having described the constituentsand the formation for the reaction product, I will now detail the methodutilized for applying it to soils. Broadly described, the methodconsists of first diluting the reaction product with water to form anaqueous solution containing from about 5 to about 25 parts of reactionproduct per 1,000 parts of water, by volume. Where said conditionsindicate it. asphalt to about 3 percent by weight is added to thereaction product just prior to dilution into the aqueous solution. Thesurface of the soil, and any base and existing surfacing, are scarifiedto the desired depth of treatment, usually 4 to 10 inches, before application of the reaction product. The aqueous solution is then appliedwith reasonable uniformity to the scarified soil surface and mixed in.

The mixing can be accomplished in various ways, but most commonly it isachieved by blading the treated soil back and forth across the treatedarea. Additional water is added, as required to thoroughly wet themixture and disperse the reaction product therein, and to bring the soilto a level of moisture content which is optimum for compaction.Thereafter, the treated soil is spread evenly over the area andcompacted. The spreading can be readily accomplished with a blade graderand the desired compaction is easily achieved by a rubber tired roller,a sheeps-foot, or a steel wheeled roller.

The treated area is then permitted to dry thoroughly. and resurfacing isundertaken, if called for.

EXAMPLE Vlll A soil stabilizing reaction product in accordance withEXAMPLE I was applied to streets with chip and seal surfacing in a NorthDakota municipality resting on a deep bed of clay with a plastic indexranging from 20 to 29, which streets had completely disintegratedbecause of severe winter weather and spring inundation. The streets werescarified to a depth of about eight inches and the reaction product wasapplied to the scarified soil and surfacing by a water truck during 2days in summer, and thoroughly mixed in by blading. Additional water wasadded to thoroughly wet the soil and after each daily application itrained. Smoothing and compaction were done, when the moisture content ofthe soil was at its optimum for compaction, by blades and aself-propelled rubber tired roller. There was very little asphalt on thestreets and no asphalt or borrow material was added. Followingtreatment, moisture was evident as far as l8 inches below scarificationdepth. After a chip and seal surfacing in the fall, the streetsweathered a winter which was extremely severe with the frost extendingto a depth of 6 feet on occasion. In the spring there were no soft spotsand except for a small frost boil, the streets showed on other signs ofdistress.

EXAMPLE [X In Kansas, a 2-mile section of asphalt surfaced road on claywith an average plastic index of about 43 was treated with a soilstabilizing reaction product in accordance with Example I. Adding 7.5gallons of the product to each 1,000 gallons of water, 40,000 gallons ofsolution were made and applied to the road and shoulders. In addition torain, 34,000 gallons of water were applied during mixing of scarifiedsoil. It was noted that although large quantities of water were addedand the soil became slick, equipment was not bogged down and mixing ofthe soil by blade was easier, drying and compaction of the soil wasfaster, traffic was getting through with little difficulty, and norutting occurred from traffic after final compaction even though itlater rained.

EXAMPLE X In Texas, a 1,000 foot section of road, constructed on a blackgumbo soil with a sand stabilized shell base 20 feet wide andapproximately 4 inches thick, and which had had many subgrade and basefailures, was treated with a soil stabilizing reaction product inaccordance with Example I. The base was scarified, care being taken notto disturb the subgrade. The reaction product was mixed with water at arate of 5 gallons of product to 1,000 gallons of water and during thecourse of a summer day was applied to the base at a rate of 1,000gallons per 5,000 square feet. Following smoothing and drying, basematerial was added, blade mixed and kept to optimum moisture content byadding water during an even distribution and blend of materials wasattained. Compaction was performed by pneumatic rol- Iers in three inchlifts, and intermittent blading was employed to keep a smooth surface.During the following months from September until May there was nomovement in the subgrade and only slight unevenness in the surface ofthe base.

EFFECT OF REACTION PRODUCT ON SOILS Initially, tests were made onsamples of a California clay with a plastic index of about which hadbeen compacted, dried and subsequently rewetted before determining theeffect of different products on the wet 20 strength. Each sample wasplaced in an extrusion mold TABLE III THE REACTION PRODUCTS INVOLVINGVARIOUS RATIOS OF SLUDGE. WATER. PETROLEUM OILS. AND CALCIUM SOURCESCalcium Spent Acid Lbs. Pressure Source Oil Water Sludge pH Per Sq. ln.

CaCo 502. None 502. 7.6 108 CaCo 502. 202. Diesel Oil 502. 502. 6.4 294CuCo Sol. 207.. Fuel Oil 502. 502. 6.8 262 C 1180, 502. None 402. 502.2.1 180 G150, 502. 202. Fuel Oil 402. 502. 1.9 264 G180, 502. 202.Asphalt 402. 502. 1.9 347 Portland Cement 502. None 50:. 4oz. 9.4 231Portland Cement Sol. 202. Fuel Oil 502. 502. 7.1 242 Portland Cement50:. 2oz. Asphalt 502. 502. 6.0 226 Fluorapatite 502. None 502. 502. 6.5246 502. 202. Fuel Oil 502. 502. 5.2 265 5oz. 2oz. Asphalt 502. 602. 3.2290 TABLE IV THE REACTION PRODUCTS INVOLVING VARIOUS RATIOS OFCOMPONENTS AND HAVING A pH of 2.0 OR ABOVE Samp Added Spent Acid Lbs.Pressure No. CaCo Oil Water Sludge pH Per Sq. In.

1 502. 402. Kerosene 202. 802. 5.15 238 3 502. None 402. 902. 2.0 200 4502. None 20:. 802. 7. I 8 164 6 502. 202. Asphalt 202. 802. 7.5 228 49402. 602. Kerosene 202. 1602. 6.9 201 54 40:. 602. Fuel Oil 202. 1602.7.3 228 TABLE V THE REACTION PRODUCTS WITH VARIOUS RATIOS OF COMPONENTSAND HAVING A pH BELOW 2.0

Sample Lbs. Pressure Per N0. CaCo, Oil Water Sludge pH Sq. In. Tests 1 23 2 502. 202. Kerosene 802. 602. 1.5 459 284 5 502. 402. Asphalt 802.602. 1.68 372 186 53 402. 802. Fuel Oil 2002. 802. 1.75 369 342 92 602.202. Kerosene 1002. 1202. 1.40 466 95 60:. 6oz. Diesel Oil 1002. 1302.1.53 392 96 602. 402. Diesel Oil 1302. 1.58 349 CONTROL NO TREATMENT 7397 13 and extruded in accordance with equipment and methods covered byA.S.T.M. Designation: D 915-61 after being submerged in water forapproximately 6 hours and drained for 4 hours.

The following tabulations show the proportions of the variousingredients used, the pH of the reaction product at dilutions of 10parts to 1,000 parts water, and the pressure required to make theextrusion in pounds per square inch. For comparison, control pressurereadings are shown for clay samples which had not been treated with anystabilizing agent.

With reference to TABLES lll-V, it is readily apparent that thosemixtures with a pH below 2.0. were definitely superior than those with ahigher pH. Moreover, in comparison with the control samples, all of themixtures listed increased the wet strength of the soil by a considerableamount.

REACTION PRODUCT WITH ANClLLARY CHLORIDE OR SULFATE COMPONENT Althoughthe described reaction products of the present invention have helpedsolve the problems of low wet bearing strength, they increased thepermeation rate of water through clay only slightly and reducedshrinkage and swell very little. in searching for solutions to theseproblems, exhaustive tests were made with clays having a plastic indexgreater than 30.

Clay/water systems are so complex that little is known about them todayin spite of a vast expenditure of time and money in their study. Theknowledge present in regard to the effect of various chemicals upon theclay/water system is even more scant. A given metal. such as aluminum,combined as a fulfact causes vastly different characteristics than thesame metal combined as a chloride. Therefore, it was necessary that allexperimentation and testing proceed on an empirical basis. Two clayswere used, one being a Tranquillity clay and the other an expansive,bentonite clay. The tests were conducted as follows.

Each sample consisted of 70 to 75 grams of clay plus the amount and kindof materials hereinafter indicated. Samples were mixed in sets of six,allowed to stand overnight, placed in molds the following afternoon, andthen dried under infra red heat lamps overnight. The following morningthey were covered with water and allowed to drain for approximately 2hours in order to obtain test results predicated upon a higher moisturecontent even though at times a zero pressure reading The purpose of thisseries of tests was to determine the relative speed with which soilsamples treated with various chemicals in combination with the reactionproduce would dry out, and how rapidly bearing values would be restoredas dehydration continued.

All of the readily available chlorides, sulfates, acetates, nitrates,and hydroxides were tested. Only the chlorides and sulfates showed adegree of compatability with the reaction product. Among them, aluminumchloride AlCL ammonium chloride NH C1, ferric chloride FeCl ferrouschloride FeCl aluminum sulfate Al (SO ammonium sulfate (NH ),SO ferricsulfate Fe (SO,) ferrous sulfate FeSO and ferrous ammonium sulfate Fe(NH(S0,), were found to be most beneficial from the standpoint of wetstrength, reduction of shrinkage and swell factor, and reduction ofplasticity index.

The following tables show the effects of treating, with variousmaterials, samples made up of Tranquillity clay. in Tables Vl through IXthe reaction product is in accordance with Example V11. With respect tothe ancillary products, AlCl represents aluminum chloride, AmClrepresent ammonium chloride, FeCl represents ferric chloride, AlSrepresents aluminum sulfate, AmS represents ammonium sulfate, FeSrepresents ferric sulfate, FeAmS represents ferrous ammonium sulfate,

and FesS represents ferrous sulfate.

All swelled very slightly. No. 3 and No. 4 looked best.

TABLE Vll SET NO. 168

AmCl AlCl Reaction Product Pressure Readings 1 .2 2.3 2.5 grams .4 1.02.25 2 .4 2.1 2.5 grams .4 1.25 2.0 3 .6 1.9 2.5 grams .45 1.30 1.8 4 .81.7 2.5 grams .60 1.35 1.8 5 1.0 1.5 2.5 grams .70 1.5 2.2 6 1.2 1.3 2.5grams .80 1.75 2.25

No. 4. No. 5 and No. 6 did not swell. No. 3 swelled slightly. No. l andNo. 2 swelled moderately.

TABLE Vlll SET NO. Reaction Pressure 170 FeS AmS AlS Product Readings l2 .2 2 l 2.5 grams 1.0 2.4 2 2 .3 2 0 2.5 grams 1.2 2.8 3 2 .4 l 9 2.5grams 1.6 3.75

FeAmS 4 .l 2.4 2.5 grams 1.75 3.25 5 .2 2.3 2.5 grams 2.0 4.25 6 .3 02.2 2.5 grams 1.6 4.25

. No. 4 did not swell. Rest swelled slightly.

TABLE 1X SET NO. Reaction Pressure 1 72 FeS AmS AIS Product Readings l.2 .2 2.1 2.5 grams .4 1.6 2.2

No. 2 and No. 6 did not swell. No. 3 and No. 5 swelled slightly. No. 1and No. 4 swelled moderately.

90 gallons (about 959 lbs.) of aluminum chloride (32 Baume, s.g. about1.28)

gallons (about 181 lbs.) of ferric chloride (45 Baume, s.g. about 1.45)

As for the sulfate mixture, which is denominated the sulfate product forconvenience of reference, various quantity production runs and test datawere also considered and the product was standardized as follows:

EXAMPLE X11 Ancillary Sulfate Product 750 pounds of aluminum sulfate Thealuminum sulfate-i 15 compatible with the react igii t a iif hit aht l thei' e ii/i2 150 pounds of femc Sl-llfate 100 pounds of ammonlum sulfategreat 1mprovement 1n wet bearmg strength and a sub- 225 gallons (about 1874 lbs of water stantral reduct1on 1n shrinkage and swell when theywater was used in i sulfate product because the were used mgetherjThefor h other constituents are normally available in dry form. use of thealummum chlor de-non chlonde m1xture in The products of EXAMPLES X] andx appear to cohluhchoh whh the macho P except that the have little or noreaction upon one another. However, shnnkage and swell factor iscompletely eliminated their use in conjunction with the reaction productof h more moderate Problem clays and Substantially the present inventionovercomes many of the problems ehminated 1n the expansive clays. Inaddition to the labh t i tic of clays and other finely divided soils.oratory tests described above, considerable field testing The followingtable shows the effects of treating Samof the ancillary products wasdone. These tests indiples made up to two-thirds Tranquillity clay andonecated that ammonium sulfate when added to the a1umithird bentoniteclay plus a small amount 0s asphalt. The num sulfate-ferric sulfatemixture was found to accelerreaction product is in accordance withExample 1, the ate the drying time of clays. and ferrous sulfate andChloride product iS in accordance it x pl chloride were found to be asgood and in some cases and the sulfate product is in accordance withExample even better than ferric sulfate and chloride. The chloridemixture appeared to be more beneficial than the TABLE X sulfate mixturein clays because of its superior ability to reduce shrinkage and swelleven though it resulted pressure Readings in slightly lower pressurereadings in certain soils. The w l 0 0 0 0 sulfate mixtureis moreeconomical, however, and ap- 7 0 0 pears to be more compatible with theuse of asphalts am 0 0 and tars. Also. the sulfate mixture is notharmful to 3 m1 Rcaflion Pmducls plant life, while the chloride mixturecould be. 40 ml Sun-ale Product 0 0 .8

Ferric ammonium sulfate proved to be an excellent 4 Reaction Producl &constituent for the ancillary products in that it gave ex- SulfateProduct 0 cellent pressure readings with minimal shrinkage and s-- 5 mlc o Product & well, however, it was found not to be available in comm]Chloride Pmducl 0 L0 mercial quantities. 6 1.2 m1. Reaction Product &

1.2 ml. Chloride Product 0 .7 1.25 2.0 PRODUCTION OF ANClLLARY PRODUCTSNo. 5 and No. 6 did not swell. Nos. 3 and 4 swelled shghtly. Variousproduction runs were made and all test data 1 and 3 swelled cons1deredto determme the best comprormse obtain- Table X] is a tabulation Showingh correlation b f quahty produciloh OhthC chlonde tween the liquidlimit, plastic index, percentage of which 15 denominated the chlondeProdhct for Conve' swell, the penetrometer readings at different timesand mence of reference. Based thereon the chloride prodh extrusionpressures, RP represents the reaction was slandal'diled a5 fOHOWSIproduct made in accordance with Example 1. CP EXAMPLE XI represents achloride product made per Example X1 and the sulfate product 1s 1naccordance w1th Example Ancillary Chloride Product X11 and AS"represents asphalt.

TABLE X1 Plas Plas. Penetrometer Readin s 1 lb. Tranqu1ll1ty clay L1m1tL1m1t lndex Swell 2hrs 3hrs 4hrs 5111's rs hrs l0hrs lZhrs Pressure ynly 48 16 32 501 0 0 0 0.1 0.75 2.30 2.75 42 10 m1 RP 44 19 25 50'; 0 00.25 0.75 2.25 3.00 I68 10 ml RP & 10 ml SP 45 29 14 33% 0 0.15 0.503.25 3.00 26 lommlRlPjtx 1 0 1 1 01 :2 s3 2( g0; 0.75 1.9 3.25 4.50 9

Rf & 5-H Sp &-

'7 5.ml I??? 5 ml CP & 5.. -3 29 5% 0 1.00 1.50 1.95 3.50 4.50-1- TABLEXl -Continued Liq. Plas. Plas. Pcnetrometer Readings Extrusion 1 lb.Tranquillity clay Limit Limit Index Swell 2hrs 3hrs 4hrs Shrs 6hrs 8hrslhrs l2hrs Pressure 8.25 ml As 46 27 19 None 1.70 2.75 4.50 426 15 ml RP& 15 ml SP 32 26 6 None 0.25 1.25 3.25 4.50+ 377 15 ml RP 8L 15 ml CP 3626 10 None 1.25 2.75 4.50 328 l0mlRP& l0mlSP& 8.25 ml As 46 28 18 None1.50 3.10 4.50+ 790 l0mlRP& l0mICP& 8.25 ml As 45 31 None 1.75 3.50450+- 41 a lb. Bentonite Clay & Liq. Plus. Plus. Penetrometer ReadingsExtrusion as lb. Tranquillity Clay Limit Limit Index Swell 2hrs 3hrs4hrs Shrs 6hrs Bhrs l0hrs l2hrs Pressure Clay only 82 21 61 0 0 0 0 0.100.70 1.25 1.80 0

00% 15 ml RP & 15 ml SP 53 27 26 0.50 0.75 1.75 2.30 3.00 4.50 288 50%15 ml RP & 15 ml CP 48 31 17 0.60 1.60 2.50 3.50 4.50 356 Table Xillustrates the degree of control that can be exercised over varioustypes of clays as the result of this invention. The tests were conductedas part ofa continuous controlled program. All samples were treated aspreviously described and tested in accordance with procedures alreadydetailed. The table shows that all of the known undesirablecharacteristics of clays have been improved or eliminated. Both thedrying time and the equilibrium of the moisture was improved. Plasticityindex was reduced by raising the plastic limit, or lowering the liquidlimit, or both. Bearing strength was recovered in very short time aftercomplete saturation as compared with untreated clays.

FIELD APPLICATION OF REACTION PRODUCT AND ANCILLARY PRODUCTS Inpractical application, various amounts of the chloride product and/or ofthe sulfate product can be used with the reaction product of the presentinvention for highly advantageous results on clays.

In general. the ancillary products are applied in equal proportion tothe reaction product with both being diluted at the rate of 5 to 20gallons of each product in 1,000 gallons of water. The application rateto the soil is usually 5 to 20 gallons of each product per foot mile ofroad. As previously indicated, the soil is generally scarified to adepth of 4 to 6 inches, the diluted chemicals applied and mixed with thesoil, and the mixture compacted with the soil at optimum moisturecontent.

The following are specific examples of field application.

EXAMPLE XIII A reaction product in accordance with Example I and achloride product in accordance with Example XI were diluted and appliedto the sub-base of a street in a Texas municipality resting on soilconsisting of clays with a plastic index of from 40 to 60. Aftertreatment, it was noted that the clay dried out very quickly, becamevery pliable and crumbly, and that compaction came easily and readily bycomparison with usual subbase soils in the area.

EXAMPLE XIV In Texas, a 1.7 mile length of asphalt surfaced road restingon clays with plastic index from 40 to 60 was reconstructed employing areaction product in accordance with Example I and a chloride product inaccordance with Example XI. The asphalt and base were scarified and thebase was treated with an aqueous solution containing 5 gallons of eachof the product per 1,000 gallons of water which was washed down into thesub-base by additional water. In areas where the base was thin and theclays appeared more troublesome, the amount of each product was doubled.The results of the treatment was considered excellent.

Thus. the reaction product of the present invention has provided a majorbreakthrough in the stabilization of clays, silts and other finelydivided soils. Utilization of the reaction product with the definedchloride product and/or the sulfate product achieves further enhancedresults, particularly on clays.

ALTERNATE METHOD OF FORMING AND APPLYING REACTION PRODUCT To practicethe alternative method, for example, I apply a selected source ofcalcium in dry, powdered or granular form to the surface of a selectedarea of soil by spreading it to give a mixture with the soil to betreated of about 2 to 10 percent by volume. If the soil surface is in acompacted condition at the time of application, it is scarified beforeor after application of the calcium to facilitate intermixing of thecalcium and the soil. If use of the ancillary products is indicated theyare also applied dry and spread over the soil surface.

Next, I apply a water solution of the spent acid sludge at a mixture ofl to 10 gallons of sludge of 1,000 gallons of water, and applied to thesoil at a rate of 500 gallons to 1,000 gallons per foot mile.

Thereafter, the reacting constituents and the soil are thoroughly mixedwhile additional water is applied to achieve thorough wetting of thesoil. The water and mixing assure uniform dispersement of the reactingconstituents throughout the soil, and the water itself enters into andcontributes to the chemical reaction. Liquid asphalt or oils may also beapplied where desired, but in climates where freeze and thaw are aproblem it should be kept near the soil surface.

When thorough mixing and dispersement of the reacting constituents inthe soil has been achieved, and while the moisture content of the soilis at optimum for compacting, the treated soil is compacted. Thechemical reaction will continue, however, until the treated soil isthoroughly dried. At this point the improved characteristics of thetreated soil will become readily apparent.

Thereafter, rewetting of the soil will not reactivate the chemicalreaction, but the soil will evidence an increased wet strength, a lowerplasticity index, a substantial reduction in shrink and swellcharacteristics,

where the ancillary products have been used, and

greatly improve water absorption and expulsion characteristics.

It should be noted that if additional hydrocarbons in the form of oilsor asphalts are indicated, these can be applied with the spent acidsludge, as can additional acid, if composition of the sludge and thenature of the soil suggest it. Although, as previously indicated, thechemical reaction incited bymoisture of the reaction productconstituents is exothermic, the generated heat is readily kept withinacceptable limits by the mass of the intermixed soil, and at the sametime contributes to the speed of the reaction. Because the heat willcause evaporation of the water, greater quantities of water may berequired than in my first method of application.

The following are examples of procedures and proportions used in thepractice of this alternative method.

EXAMPLE XV Using as a source of calcium, waste lime from a sugarprocessing plant, a quarter mile of road 28 feet wide is first scarifiedto a depth of 8 inches. Then said lime is spread on the road at a rateof 4 tons per mile.(l ton of the lime being approximately 1 cubic yard),and intermixed with said scarified soil by blading the soil and limewith a grader or by use of a pulvimixer. Thereafter, a spent sulfuricacid is intermixed with water at the rate of 5 gallons of acid to 1,000gallons of water and applied to the soil and lime mixture at the rate of500 gallons per foot mile. Additional water is then applied to bring thesoil to optimum moisture content for compaction, the mixture iscompacted, and allowed to dry thoroughtly.

EXAMPLE XVI Following the same procedure as in Example XV, exceptapplying the lime at a rate of 8 tons per foot mile.

EXAMPLE XVll Following the same procedure as in Exhibit XVI, exceptintermixing said acid and water at the rate 0f 10 gallons of acid per1,000 gallons of water.

As these examples suggest, it is not only possible and economicallyfeasible in proper situations to add con- 'siderably greater quantitiesof the reaction product constituents when this alternative method isused, but

since intermixing is accomplished at the job site rather than at theplant, much greater flexibility in tailoring reaction product mix to theparticular soil condition being greated is possible.

In certain applications it may be desirable to incorporate borrowmaterials into the soil at the same time as it is treated with thereaction product. This can be achieved either by spreading the borrowmaterial over the soil surface in the same manner as the dryconstituents, or it is possible to premix granular borrow material withthe dry constituents and deliver it to the job site in mixed form forspreading.

Although the present invention is described in terms of particularconstituents, and ranges thereof, and manner of making and using thesame, it is recognized that departures may be made therefrom within thescope of the invention as defined in the appended claims and that allmatter in the foregoing description is to be interpreted as illustrativeonly.

I claim:

1. A soil stabilizing agent comprising: the reaction product of acalcium compound selected from the group consisting of calciumcarbonate, calcium fluorapatile, calcium phosphate, calcium sulfate,calcium oxide, and Portland cement and a sulfuric acid sludge having notless than 60 percent acid nor more than 35 percent entrainedhydrocarbons combined in a sufficient quantity of water to maintainfluidity of the resultant product, said constituents being combined insuch type and quantity as to provide the reaction product with a pH ofless than 7.

2. A soil stabilizing agent as described in claim 1, in which:

a liquid mineral hydrocarbon is added to said mixture in an amount lessthan 10 percent by weight of said reaction product.

3. A soil stabilizing agent as described in claim 1, in

which:

said constituents are selected in type and quantity to provide saidreaction product with a pH ofless than 5.

4. A soil stabilizing agent as described in claim I, in

which:

said constituents are selected in type and quantity to provide saidreaction product with a pH of less than 2.0

5. A soil stabilizing agent comprising:

the reaction product of ID to 50 percent by weight of a source ofcalcium selected from the group consisting of calcium carbonate, calciumfluorapatite, calcium phosphate, calcium sulfate, calcium oxide, andPortland cement; saic calcium source being intermixed in 20 to 50percent water to which is added 20 to percent by which sulfuric acidsludge being not less than 60 percent by weight acid and having not morethan 35 percent by weight entrained hydrocarbons, said consituents beingselected as to type and quantity to provide said reaction product with apH of less than 7.

6. A soil stabilizing agent as described in claim 5, in

which:

said constituents are so selected by type and quantity as to providesaid reaction product with a pH of less than 5.

7. A soil stabilizing agent as described in claim 5, in

which:

a liquid mineral hydrocarbon is added to the reaction product tocomprise not more than percent by weight thereof. 8. A soil stabilizingagent as described in claim 5, in which:

said percentages by weight of said source of calcium in said reactionproduct are to percent; said percentages by weight of said sulfuric acidsludge in said reaction product are to 55 percent; said sulfuric acidsludge is aged to the condition where itis purplish in color; saidpercentages by weight of said water in said reaction product are 25 topercent; and said constituents are selected as to type and quantity toprovide said reaction product with a pH of less than 3. 9. A soilstabilizing agent as described in claim 5, in which:

said source of calcium is calcium carbonate and constitutes 15 to 20percent by weight of said reaction product; said sulfuric acid sludge isa spent acid sludge having not less than 80 percent acidity nor morethan 20 percent entrained hydrocarbons and being aged to the conditionwhere it is purplish in color, and said spent acid sludge constitutes topercent by weight of said reaction product; and said reaction producthas a pH of less than 2. 10. The method of forming a soil stabilizingagent comprising the following steps:

first, adding a source of calcium, said source being selected from thegroup consisting of calcium carbonate, calcium fluorapatite, calciumphosphate, calcium sulfate, calcium oxide, and Portland cement, to aquantity of water sufficient to provide a fluid mixture; and, second,adding to said fluid mixture a quantity of sulfuric acid sludge havingnot less than percent acid nor more than 35 percent entrainedhydrocarbons sufficient to reduce the pH of the mixture to below 7,while maintaining said mixture at a temperature of less than l80F. ll.The method of forming a soil stabilizing agentas described in claim 10,in which:

said calcium source constitutes 15 to 25 percent by weight of the finalmixture; said water consitutes 20 to 45 percent of the final mixture;and said sulfuric acid sludge is a spent sulfuric acid aged to thecondition where it is purplish in color, and constitutes 30 to 55percent by weight of the final mixture. 12. A method of stabilizingsoils, comprising: applying to the soil from 2 to 40 parts by volume ofasoil sta- LII bilizing agent to 1,000 parts by volume of water, saidagent comprising the raction product of a calcium compound selected fromthe group consisting of calcium carbonate, calcium fluorapatite, calciumphosphate, calcium sulfate, calcium oxide, and Portland cement and asulfuric acid sludge having not less than 60 percent acid nor more than35 percent entrained hydrocarbons conbined in a sufficient quantity ofwater to maintain fluidity of the resultant product, with said elementand acid being combined in such type and quantity as to provide theresulting product with a pH of less than 7.

13. A method of stabilizing soils, as described in claim 12, in which:

said soil stabilizing agent is applied to the soil in 5 to 25 parts byvolume of agent to 1,000 parts by volume of water. 14. A method ofstabilizing soils, as described in claim 12, in which:

said source of calcium constitutes 14 to 23 parts by weight of the agentand is intermixed with 26 to 29 parts by weight of water and 25 to 54parts by weight of said sulfuric acid sludge; and said agent has a pH ofnot more than 2. 15. A method of stabilizing soils as described in claim13, in which:

said agent further includes a source of liquid mineral hydrocarbon. 16.A method of stabilizing finely divided soils as described in claim 15,in which:

said soil to be treated is first scarified to the desired depth oftreatment; said source of an element of known stabilization benefit inthe soil is a source of calcium selected from the group consisting ofcalcium carbonate, calcium fluorapatite, calcium phosphate, calciumsulfate, calcium oxide, and Portland cement; said source of acid is asulfuric acid sludge having an acidity of at least 60 percent and ahydrocarbon content of not is excess of 30 percent; and said mixture isbrought to a moisture content optimum for compaction before it iscompacted. 17. A method of stabilizing finely divided soils as describedin claim 16, in which:

said source of calcium is applied in sufficient quantity to constitute amixture of from 2 to 20 percent by volume with said soil; and saidsulfuric acid sludge is applied to said mixture of calcium source andsoil in a water solution comprising two to ten gallons of surruric acidsludge to 1,000 gallons of water, applied to said mixture at the rate of250 gallons to l,000 gallons per foot mile.

33 3? UNlTED STATES PATENT OFFICE CERTIFICATE OF CQRRECYIQN Patent: No.3, 7 ,43 Dated April 8, 1975 Inventor(s) Gordon L. Schneider It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Column 20, line 24, "fluorapacile should read -fluorapatite-.

Column 20, line 41, there should. be a space between "of" and "less"Column 20, line 47, there should be a period after "2.0".

Column 20, line 53, "saic" should read -said Column 20, line 55, "which"should read weight Column 22, line 2, "raction" should read reactionColumn 22, line 8 I "combined" should read combined Column 22, line 50,"surruric" should'read sulfuric En'gncd and Sealed this ninth D a y 0fSeptember 1 9 75 [SEAL] Arrest:

RUTH C. MASON C. MARSHALL DANN Arresting Officer (mnmissimwr of Parentsand Trademarks Q ifigg? E3) STAKES PATENT OFFIQE wg'w'zwa I1: YTi 4 v Fijibrirdfiifimir Ur QJQRRELTIQN Patent No 3 13 6 43 Dated April 8 P 1975invasions} "IQEZ'AOE 1., .scinaelder If is certified that error appearsin the above-identified patent and rhat said Letters Patent are herebycorrected as shown below:

\ d W a! Column .20; line 24., fluorapatlleshould read ---fluorapat1te-.

Column 26; line ll, there should. be a space between "of" and "less"(Zolumn 2G 417 there should be a. period after 2,O".

Q m w P H v column 40, line 233, sales should read sald Column 20,, line55 "which should read weight Column 22 line 2,; "reaction? should readreaction Column 22 3.111% 8, "combined" should read combined Column 22,llne 50, "surruric" should'read sulfuric L wk tas O ninth ay 0?September 1975 QEEAU sum r. MASDH c MARSHALL DANN arresting OfficerCommissioner uflarcnrs and Tradvmarks a ib m9

1. A SOIL STABILIZING AGENT COMPRISING: THE REACTION PRODUCT OF ACALCIUM COMPOUND SELECTED FROM THE GROUP CONSISTING OF CALCIUMCARBONATE, CALCIUM FLUORAPATILE, CALCIUM PHOSPHATE, CALCIUM SULFATE,CALCIUM OXIDE, AND PORTLANT CEMENT AND A SULFURIC ACID SLUDGE HAVING NOTLESS THAN 60 PERCENT ACID NOR MORE THAN 35 PERCENT ENTRAINEDHYDROCARBONS COMBINED IN A SUFFICIENT QUANTITY OF WATER TO MAINTAINFLUIDITY OF THE RESULTANT PRODUCT, SAID CONSTITUENTS BEING COMBINED INSUCH TYPE AND QUANTITY AS TO PROVIDE THE REACTION PRODUCT WITH A PH OFLESS THAN
 7. 2. A soil stabilizing agent as described in claim 1, inwhich: a liquid mineral hydrocarbon is added to said mixture in anamount less than 10 percent by weight of said reaction product.
 3. Asoil stabilizing agent as described in claim 1, in which: saidconstituents are selected in type and quantity to provide said reactionproduct with a pH ofless than
 5. 4. A soil stabilizing agent asdescribed in claim 1, in which: said constituents are selected in typeand quantity to provide said reaction product with a pH of less than 2.05. A soil stabilizing agent comprising: the reaction product of 10 to 50percent by weight of a source of calcium selected from the groupconsisting of calcium carbonate, calcium fluorapatite, calciumphosphate, calcium sulfate, calcium oxide, and Portland cement; saiccalcium source being intermixed in 20 to 50 percent water to which isadded 20 to 80 percent by which sulfuric acid sludge being not less than60 percent by weight acid and having not more than 35 percent by weightentrained hydrocarbons, said consituents being selected as to type andquantity to provide said reaction product with a pH of less than
 7. 6. Asoil stabilizing agent as described in claim 5, in which: saidconstituents are so selected by type and quantity as to provide saidreaction product with a pH of less than
 5. 7. A soil stabilizing agentas described in claim 5, in which: a liquid mineral hydrocarbon is addedto the reaction product to comprise not more than 10 percent by weightthereof.
 8. A soil stabilizing agent as described in claim 5, in which:said percentages by weight of said source of calcium in said reactionproduct are 15 to 25 percent; said percentages by weight of saidsulfuric acid sludge in said reaction product are 30 to 55 percent; saidsulfuric acid sludge is aged to the condition where it is purplish incolor; said percentages by weight of said water in said reaction productare 25 to 45 percent; and said constituents are selected as to type andquantity to provide said reaction product with a pH of less than
 3. 9. Asoil stabilizing agent as described in claim 5, in which: said source ofcalcium is calcium carbonate and constitutes 15 to 20 percent by weightof said reaction product; said sulfuric acid sludge is a spent acidsludge having not less than 80 percent acidity nor more than 20 percententrained hydrocarbons and being aged to the condition where it ispurplish in color, and said spent acid sludge constitutes 50 to 55percent by weight of said reaction product; and said reaction producthas a pH of less than
 2. 10. The method of forming a soil stabilizingagent comprising the following steps: first, adding a source of calcium,said source being selected from the group consisting of calciumcarbonate, calcium fluorapatite, calcium phosphate, calcium sulfate,calcium oxide, and Portland cement, to a quantity of water sufficient toprovide a fluid mixture; and, second, adding to said fluid mixture aquantity of sulfuric acid sludge having not less than 60 percent acidnor more than 35 percent entrained hydrocarbons sufficient to reduce thepH of the mixture to below 7, while maintaining said mixture at atemperature of less than 180.degree.F.
 11. The method of forming a soilstabilizing agent as described in claim 10, in which: said calciumsource constitutes 15 to 25 percent by weight of the final mixture; saidwater consitutes 20 to 45 percent of the final mixture; and saidsulfuric acid sludge is a spent sulfuric acid aged to the conditionwhere it is purplish in color, and constitutes 30 to 55 percent byweight of the final mixture.
 12. A method of stabilizing soils,comprising: applying to the soil from 2 to 40 parts by volume of a soilstabilizing agent to 1,000 parts by volume of water, said agentcomprising the raction product of a calcium compound selected from thegroup consisting of calcium carbonate, calcium fluorapatite, calciumphosphate, calcium sulfate, calcium oxide, and Portland cement and asulfuric acid sludge having not less than 60 percent acid nor more than35 percent entrained hydrocarbons conbined in a sufficient quantity ofwater to maintain fluidity of the resultant product, with said elementand acid being combined in such type and quantity as to provide theresulting product with a pH of less than
 7. 13. A method of stabilizingsoils, as described in claim 12, in which: said soil stabilizing agentis applied to the soil in 5 to 25 parts by volume of agent to 1,000parts by volume of water.
 14. A method of stabilizing soils, asdescribed in claim 12, in which: said source of calcium constitutes 14to 23 parts by weight of the agent and is intermixed with 26 to 29 partsby weight of water and 25 to 54 parts by weight of said sulfuric acidsludge; and said agent has a pH of not more than
 2. 15. A method ofstabilizing soils as described in claim 13, in which: said agent furtherincludes a source of liquid mineral hydrocarbon.
 16. A method ofstabilizing finely divided soils as described in claim 15, in which:said soil to be treated is first scarified to the desired depth oftreatment; said source of an element of known stabilization benefit inthe soil is a source of calcium selected from the group consisting ofcalcium carbonate, calcium fluorapatite, calcium phosphate, calciumsulfate, calcium oxide, and Portland cement; said source of acid is asulfuric acid sludge having an acidity of at least 60 percent and ahydrocarbon content of not is excess of 30 percent; and said mixture isbrought to a moisture content optimum for compaction before it iscompacted.
 17. A method of stabilizing finely divided soils as describedin claim 16, in which: said source of calcium is applied in sufficientquantity to constitute a mixture of from 2 to 20 percent by volume withsaid soil; and said sulfuric acid sludge is applied to said mixture ofcalcium source and soil in a water solution comprising two to tengallons of surruric acid sludge to 1,000 gallons of water, applied tosaid mixture at the rate of 250 gallons to 1,000 gallons per foot mile.